Method of controlling the color in vacuum tube lamps



Patented Oct. 6, 1931 UNITED STATES PATENT OFFICE LEO L. BECK, OF JACKSON HEIGHTS, NEW YORK, ASSIGNOR TO CLAUDE NEON LIGHTS,

INC., 01 NEW YORK, N. Y A CORPORATION OF NEW YORK METHOD OF CONTROLLING THE COLOR IN VACUUM TUBE LAMPS No Drawing.

This invention relates to gaseous conductor tube lighting systems, so called, which are systems in which the passage of a high potential alternating current through a column of more or less rarefied gas in a tube causes the tube content-s to glow. and radiate light. More particularly, the invention relates to such systems in which the tube ,contents comprises a rare gas, such as neon, and

o a metallic vapor, such as mercury vapor which mixture it is customary to maintain within the tube at apressure of about 5% mm.

of mercury.

The light emitted from a mixture of such gas and vapor is a result of the mixture of the light emitted from each gas vibrating alone. Thus the greenish blue light of the vibrating mercury vapor is mixed with the orange red light of the neon gas to produce 0 a blue color which is utilized advantageously in advertising sign lighting and the like. It has been found that, as the mercury vapor tends to condense and thus becomes less diffused throughout the tube, that the light 5 emitted by the tube changes from a blue color and assumes a pinkish tinge which becomes more pronounced as the diffusion of the mercury vapor decreases.

vIn one of its aspects, this invention has for 0 its object the control of the light emitted from a lighting system containing a rare gas, such as neon, and a metallic vapor, such as mercury vapor, to produce either a blue or say a pink colored light at will.

I have discovered that the tendency of the mercury vapor to condense, depends, among other things, upon two factors, to wit, the temperature of the tube and the pressure of the gas in the tube. Contrary to what might be expected, by increasing the pressure of the gas within the tube, the condensation'of the mercury vapor is retarded. Similarly an increase in the temperature of the tube retards the condensation of the mercury.

These factors, are met with in the operation of gaseous conductor tube lighting systems used in connection with out-of-door advertising signs since a tube containing say neon and mercur under usual pressures is found to change rom a blue color and assume a Application filed February 10, 1987. Serial No. 167,873.

pinkish tinge as the temperature of the surrounding atmosphere is reduced.

In another aspect, therefore, the invention has for its object the stabilization of the color of gaseous conductor tubes designed for operation under varying temperature conditions. For instance, that temperature may be determined which is the lowest temperature at which the sign will be called upon to operate, and the pressure of the mercury vapor and gas in the tube may be made such that the color of the light emitted from the tube will remain blue throughout the entire range of temperature to which the lighting system is subjected, or vice versa As a guide inputting the invention into practice, the following table is illustrative of the effect of gas pressure and'temperature on tubes containing a mixture of neon gas and mercury vapor. Thus in the column on the left that barometric pressure of the tube contents is indicated which is necessary to insure that a blue color will be maintained at the surrounding temperature shown in the column on the right and below which temperature the tube assumes say a pinkish tinge.

Temp. tubes become blue Pressure mm. Hg. Degrees F. 2 64 Thus, from the table given above it is possible to provide a gaseous conductor tube, which will maintain a blue color at any temperature above a predetermined minimum. For instance, if the predetermined minimum temperature in which the advertising sign operates is 40 F., a pressureof 7 mm. of mercury on the gas within the tube will insure the emission of a blue light at all times from the tube.

If the minimum temperature is say 32 F., a pressure of 13 mm. on the tube contents will insure the emission of blue light at all time In some climates where the temperature is likely to drop to 14 F., it has been found necessary to place the tube contents under a pressure of 30 mm.

It will thus be seen that a tube can be designed with the aid of the above table which will emit blue color under all normal temperature conditions and will operate even in winter on the coldest days without the color emitted by the rare gas appearing.

What I claim is:

1. The method of stabilizing the light emitted by a glow discharge tube lamp containing mercury vapor and neon comprising subjecting the tube contents to a pressure in excess of 8 millimeters of mercury.

52. The method of stablizing the color of glow discharge tube lamps containing mercury vapor and neon comprising subjecting the tube contents to a pressure in excess of 8' millimeters of mercury and less than 50 millimeters.

3. The method of stabilizing the color of light emitted by a glow discharge tube lamp at atmospheric temperatures not greater than 38 F. containing mercury vapor and neon gas comprising subjecting the tube contents to a predetermined pressure in excess of 8 millimeters of mercury.

4. A glow discharge luminescent tube containing mercury and neon, the filling pressure of the neon being in excess of 8 millimeters of mercury.

5. A glow discharge luminescent tube containin mercury and neon, the filling pressure 0 the neon being between 8 and 30 millimeters of mercury.

6. A low discharge tube containing mercury an a rare gas, said gas having a high filling pressure in excess of 8 millimeters of mercury, the combination of gas at high pressure and mercury providing a tube which emits a blue light at temperatures below 38 Fahrenheit.

In testimony whereof I afix my signature.

LEO L. BECK. 

